(a) Field of the Invention
The present invention relates to a hydraulic control system of an eight-speed automatic transmission for a vehicle.
(b) Description of the Related Art
A typical automatic transmission includes a torque converter and a powertrain of a multiple speed gear mechanism connected to the torque converter. In addition, a hydraulic control system is provided for selectively operating at least one operational element included in the powertrain according to a running state of a vehicle.
The powertrain includes a compound planetary gear set, including at least two simple planetary gear sets to achieve the required multiple speeds, and a plurality of friction members. The hydraulic control system selectively operates the friction members of the powertrain according to driving conditions.
Recently developed automatic transmissions achieve eight forward speeds for performance and fuel efficiency, and therefore a hydraulic control system for such an eight-speed automatic transmission, that provides precise control and good durability of the transmission, is required.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.